Durability evaluation of concrete for high temperature applications under thermal fatigue

Abstract

The paper aims to advance on the development of self-compacting concrete (SCC) for use in the construction of thermal energy storage infrastructures. Two fundamental aspects have been addressed: 1) The design of concrete, to support the processes of cement paste dehydration, the volume variation and the control of cracking, without compromising the integrity of the system. 2) The use of additives that improve the concrete thermal fatigue performance. Two additives have been used, the addition of polyvinyl alcohol (PVA) dispersed in the cement matrix to control the appearance of cracks and to maintain microstructure stability, and the incorporation of carbon nano tubes (CNT) and carbon microfibers (CMF) with polypropylene fibers (PPF) to control the stress of thermal fatigue. The thermal performance of the concretes was evaluated after been exposed to heat/cool cycles (290ºC to 550ºC). The parameters addressed are: mechanical, microstructure, crack size, porosity and electrical resistivity. The results indicate that after the first heating inducing mechanical strength loss the system mechanically stabilize. The cracks produced due to the changes in volume during heat cycles are lower with PVA and the electrical resistivity of the concretes is significantly reduced with the incorporation CNT+CMF favoring the self-sensing performance.